The passage describes the development of smaller, hand-held cameras enabled by the invention of the dry plate photographic process. Specifically, it notes that:
1) The dry plate process allowed for instantaneous exposures without special equipment, leading manufacturers to design smaller, hand-held cameras.
2) One of the first such designs was Thomas Bolas' 1881 "Detective" camera, a plain box camera intended for covert use.
3) Many 1880s designs were magazine cameras that could pre-load multiple dry plates for one-after-another exposure, though they remained heavy and required darkroom work.